Arithmetic Sequences and Series

What is the 7th term in the sequence 7, 11, 15, … ?

What is the common difference in the sequence -7, -5, -3, -1, … ?

The 6th term in the arithmetic sequence 18, 11, 4, …

Which of the following is NOT an arithmetic sequence?
1. 48, 24, 12, 6, 3, ...
2. 3, 7, 11, 15, 19, ...
3. 1, $$\frac{1}{2}$$ , 0, $$-\frac{1}{2}$$ , ...
4. 1, 0, -1, -2, -3, ...

It is a sequence that has a common difference.

Insert 5 arithmetic means in the sequence: -3, ___, ___, ___, ___, ___, 12

Terms between any two non-consecutive terms of an arithmetic sequence.

A theater has 32 rows of seats. If there are 26 seats in the 1st row, 30 in the 2nd, 34 in the 3rd, and so on, how many seats are there in all? Assume the pattern continues.

Sum of definite number of terms of an arithmetic sequence

Correct formula for finding the Arithmetic Series?